For more than a decade, the powerhouse class action law firm Milberg Weiss engendered fear and loathing in the corporate boardrooms targeted with multimillion-dollar lawsuits alleging financial shenanigans that had defrauded investors. And through most of that time, the leaders of the firm, including William Lerach and Melvyn Weiss, batted away accusations that they made improper payments to plaintiffs in order to secure the lucrative litigation all for themselves.

Today, those denials are inoperative, the firm has broken up, and Lerach and Weiss are headed to federal prisons after pleading guilty to felony charges. But the head of the American Tort Reform Association, Sherman Joyce, says the full story of ethical misconduct by plaintiffs’ lawyers in securities fraud suits remains to be written — and he wants Congress to investigate.

Joyce notes that, in a pre-sentencing interview with The Wall Street Journal, Lerach claimed his firm was just following an “industry practice” when it solicited and then paid shareholders who served as plaintiffs in securities suits. If Congress has time to investigate steroid use by baseball players, Joyce says, it ought to have time as well to look into the extent of unethical conduct over the years by plaintiffs lawyers in securities cases.

The majority Democrats in Congress, so many of whom are beholden to the financial largesse of trial lawyers, are unlikely to undertake that investigation. But the indictments against Weiss, Lerach and their firm allege they were all engaging in this misconduct at least since the early 1990s and as late as 2005 — even after the criminal investigation in their case was under way. According to the indictments, the firm paid various plaintiffs more than $11 million in kickbacks in cases, against dozens of companies, that netted the firm as much as $250 million in legal fees.

Early on, Milberg Weiss suggested the prosecution was a politically motivated attack by a business-friendly Bush Justice Department. In fact, as recounted by Fortune editor at large Peter Elkind, the investigation was spearheaded by a career prosecutor in Los Angeles and self-identified Democrat, Richard Robinson. And the inquiry began a year before Bush took office — and in quite a roundabout way: A domestic violence defendant in Cleveland ratted on a friend in Los Angeles, who then told the feds about an insurance fraud involving Steven Cooperman, a wealthy former eye doctor. Cooperman, it turned out, was Milberg Weiss’ go-to plaintiff in dozens of shareholder suits. After his conviction for insurance fraud in 1999, he spilled the beans on all the kickbacks he received from the firm.

In Lerach’s out-of-court apologia, he claimed no client was harmed by the conduct. Maybe not. But the firm profited by maneuvering to be the first to file against a company and gaining control of the class action suit. And to do so, it had to certify under oath that no one had been paid to bring the suit. “Outright lying to judges under oath is clear-cut,” says Richard Nagareda, an expert on civil litigation at Vanderbilt Law School. “This is not a situation in which people are being put in prison because of borderline close calls.”

Next month, Lerach is to begin serving a two-year sentence for conspiracy to obstruct justice and making false statements. Weiss is expected to get 33 months for his guilty plea to a single racketeering charge. Two other Milberg Weiss lawyers already had pleaded guilty; the indictment against the firm is still pending.

A third prominent trial lawyer is soon headed to some serious time behind bars. Richard Scruggs, the Mississippi lawyer who masterminded the $206 billion tobacco litigation settlement in the late 1990s, faces a likely five-year sentence for attempting to bribe a state court judge. At the time, the judge was presiding over a case that would set Scruggs’ fee for representing property owners seeking insurance payouts for damages wrought by Hurricane Katrina.

With plaintiffs lawyers so notoriously in the news, the trial lawyers’ organization has been notably silent. The American Association for Justice, or AAJ — previously named the Association of Trial Lawyers of America — has had nothing to say about Lerach and Weiss. The group’s president, Kathleen Flynn Peterson, did comment after Scruggs’ indictment in December, but only to attack the “slick talk from those that want to brand trial attorneys as villains.”

The trial lawyers’ silence is “understandable,” Nagareda says, not only because their peers are under scrutiny but also because critics of the trial bar will try to depict the misconduct as typical of plaintiffs lawyers. “It’s not the norm,” Nagareda says. But he is not ready to dismiss the recent cases as nothing more than a few rogue lawyers. “If you turn over stones, will you find other abuses?” he asks rhetorically. “Is this pervasive? I don’t know.”

Congress could apply its potentially significant oversight powers to finding out, then move on to consider some new federal rules to govern securities fraud suits beyond those enacted a dozen years ago. But that shouldn’t be expected in the current political climate: At $1.9 million donated so far, the AAJ political action committee is the 16th most generous PAC toward 2008 congressional candidates — and 96 percent of its money has gone to Democrats.

Kenneth Jost is the Supreme Court editor for CQ Press. For a complete listing of his columns, click here.